This invention relates to a device for measuring heartbeat rate, and more particularly to a device for detecting and processing a signal carrying the heartbeat data and for indicating the heartbeat rate to the user of the device.
While participating in top sports, sports training and fitness training, it is important to measure the heartbeat rate reliably and without interruption during the performance, without the performance disturbing the measurement. Various handheld measuring devices based on the measurement of the ECG heartbeat rate signal from e.g. the user's fingertips have been designed for this purpose, as a well as a measuring devices based on telemetric wireless transmission between a separate transmitter attached to the body and a receiver worn on the wrist, cf. Finnish Patents 55761 and 68734.
Measurements based on contact are always somewhat inaccurate, depending on the user's anatomy and the way the device is held in the hand. Holding the device in the hand and observing the values on the display also needlessly draw the attention of the user to the device during the performance. On account of their reasonable price and measuring accuracy and ease of use, devices of this type have been used mainly for amateur performances. Wireless devices, in which the heartbeat rate signal is monitored continuously by means of ECG sensors that are stationary fixed to the body, have a measuring accuracy slightly better than that of the above-described hand-held devices, and due to the continuous measuring principle it has been possible to include pulse monitoring functions and statistical functions in these devices. The price of these devices has, however, been relatively high, which has limited their use mainly to professionals and sports clubs.
Continuous progress in electronic circuitry and manufacturing techniques has reduced the price of different measuring devices so that even casual users can now afford to buy them. However, the known devices are still divided into two groups according to their properties, which causes contradiction between the ease of use of the (handheld measuring devices), and the versatility of properties and measuring accuracy of the (wireless measuring devices).